What age is okay to start having them watch educational stuff on tablets/TV?

Our daughter is 2 months old in 4 days. Since she was born we didn't let her look at like the tablet screen if she is listening to music, or Seasame Street songs. What age is it okay for her to start watching stuff like this? We love her but unless something is right in front it her she panics and cries. Today was the first day she was on her play mate thing (it finally just arrived) and she was in awe. But we don't wanna rely on just that. Any experience with this sort of thing?